Method of and machine for bending tubes



(No Model.)

` YMETHODAOBAND MAGHINBFOR BBNDING TUBES. No. 506,157. y I f Patented001;.. s, 189s.)

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UNITED) SrmussY PATENT OFFicE..

ROBERT CLARKE, OF GRAVESEND, NEW YORK.

METHOD OF AND MACHINE FVOR BENDING TUBES.

SPECIFICATION forming part of Letters Patent No. 506,157, dated October3, 1893.

Application filed March l, 1893. Serial No. 464.242. (No model.)

To all whom it may concern: l

Be it known that I, ROBERT CLARKE, residing in Sheepshead Bay, (P. O.,Gravesend,) Kings county, New York, have invented certain new and usefulImprovements in Methods of and Machines for Bending Tubes, of which thefollowing is a specification.

My invention relates to methods of and apparatus for making bent tubesof different metals, as for instance, such tubes as are used for handrails, boiler tubes, traps, &c., and my invention consists in bendingsaid tubes by forcing them into suitably formed channels in molds, whileat the same time forcing through the tubes and at a greater rate ofspeed, a series ofy hard metal spheres, as fully set forth hereinafterand as illustrated in the accompanying drawings, in which- Figure l is aplan view illustrating the apparatus employed in carrying out myinvention; Fig. 2, a sectional plan of the said apparatus, showing alsothe forcing means. Fig. 3 is a section ou the line 8 3, Fig. 2. Fig. 4is a plan showing a dierent form of die. Fig. 5 is an elevation alsoshowing a different form of die; Fig. 6, a sectional elevation, showinga die as used for curving spiral tubes.

The operative partsl of the bending apparatus are mounted upon a base,A, of any suitable construction, said operative parts consistingessentially of die sections having between them an opening or channelcorresponding to the form to be impartedv to a tube. According to thepurpose to which the bent tube is to be applied, this form maycorrespond to a part of a circle lying all in one plane, or it mayconform to a spiral as is requisite in bending tubes to a spiral formfor boilers, zc., or the curve instead of being circular may correspondto part of an ellipse or oval as circumstances require.

It will be evident that the form and construction and arrangement of thedie sections will depend upon the form to be imparted to the tube, butthere is generally an inner section, B, and an outer section C, and Iprefer to make the inner section in the form of a wheel having anannular groove at the periphery and the section C, whatever its form,will also have a groove so as to form with the groove in the section B,a channel of the proper shape.

As shown in Figs. l, 2 and 3, the section C is a block recessed toreceive about one-half the diameter of the wheel section B andconforming tothe periphery of the latter, and

having in the part opposite the said periphmerely pushing the said tubeendwise into said channel would not result in forming a perfect bend,that is', 4the tube would be creased and wrinkled, if not llattened inthe eort to push it through the curved channel.

I therefore provide for means for maintaining the cylindrical form ofthe tube notwithstanding the pressure and the variations of pressurewhich vmust beput upon it in forcing it through the channel, the sameconsisting in inserting in the tube a number of spheres e, preferably ofhardened steel, and

which accompany the tube in its movements through the channel and whichare withd rawn after the tube has been properly bent. I have discoveredthat if the spheres are pushed with the tube at the same speed at whichthe latter moves, the bending is not perfectly accomplished, but on thecontrary, lthe tube is wrinkled and distorted so that it is difficult toremove the spheres after the bending has been eected. I thereforeprovide means whereby the spheresare caused to travel through the tubeat a greater speed than that at which the tube is introduced -into thechannel, so that the spheres have a sort of a rolling action tending toiiatten and draw out the metal and preserve the absolute cylindricalform of the interior of the tube, notwithstanding the variations in thestrain at diiferent parts of the tube. While different means may beemployed for imparting this difference in motion of travel to the tubeand to the internal spherical balls or mandrels, I have found that aneffect-ive means of operation consists in forcing the tube into itschannel by means of a hollow plunger D, moving l at the proper rate ofspeed and in forcing the series of balls ICO through the tube by meansof a solid cylindrical plunger or rod E traveling at a higher speed thanthat of the plunger D. The sections B, C of the die are each separablefrom the base A, the wheel or disk B being held by a detachable bolt orpin 8 and the section C by bolts or pins 9. Various means for inlpartingthis dierential movement to the two parts will be evident to any oneskilled in the art. As shown in Fig. 2, the said means consists of ahandwheel I, the hub D of which is hollow and constitutes the hollow plungerD upon which the ends ot' the tube X bear, a hollow tubular extension 4of the plunger D having threads fitting a threaded opening in a standard5, the threads being at such a pitch that the revolution of the wheel Iwill impart the requisite degree of traveling movementto the hub orplunger D. The plunger D and the tubular extension 4 are also threadedwith a. pitch very much greater than that of the exing curved metaltubes, of a die consisting of two sections having a curved channelbetween tension 4 and adapted to the threads upon the plunger E, so thatwhen the wheel is turned i-t will impart to the plunger E a quick,forward, traveling movement, and the wheel itself will also travelforward in its bearing 5 but at a much less rate of speed. Thedifference between the speed of one plunger and the other may be anydifference which is found most eectlve. As a general thing, I t

` a tube bending machine, and with a series of .spheres adapted to bearranged Within the find that a difference of five to one will, in manycases, be sufficient; but it may be greater or less as circumstancesdemand. The construction illustrated in Figs. 1, 2 and 3 will sufficewhere the tube is to be bent to anything less than a half circle, orwhere it is to be bent to a full circle, the section C should extendcompletely around the section B of the die, as illustrated in Fig; 4;and where the tube is to be bent to a spiral form, the section B is setat an angle to part of the section O, as illustrated in Fig. 6. It isnot necessary that the section C should be a solid block; it may consistof a series of grooved rollers, 7, as illustrated in Fig. 5, and thesection B itself may consist of aV series of grooved rollers asillustrated in dotted lines, Fig. 2. Where the section B consists of awheel, it may be divided longitudinally into two sections upon the planeillustrated by dotted lines y, Fig. 5, so that if more pressure comes lupon one section or the other, such section may move more readily or ata greater speed than the other, and when the outer section consists ofgrooved rolls 7, they may likewise be divided centrally upon the sameplane.

Without limiting myself to the precise construction and arrangement ofparts shown, I claim- 1. The within described improvement in themanufacture of bentv metal tubes, the same consisting in pushing thetube under endwise pressure into a curved channel and at the same timepnshingthrough the tube at a greater speed a series of spheres,substantially as set forth.

`2. The combination in a machine for makthem for the reception of thetube to be bent, a series of spheres arranged within the tube to bebent, and means for pushing the tube through the channel at one speedand the spheres through the tube at a greater speed,

. substantially as set forth.

3. The combination with the dies B, C, of

ROBERT CLARKE.

Vitnesses:

C. MOORHEAD, JOSEPH H. SAUNDERS.

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